A collimator-less technique for spatial non-linearity correction of PET detectors

A new spatial calibration technique for PET detectors has been developed and successfully implemented. It has practical advantages over existing methods in that the usual requirements of bulky collimators and an intensely radioactive source are obviated. Coincidence events are collected using a relatively weak (~0.1 mCi) point source suspended without any collimation at a series of locations within the field of view of the scanner. The calculation of corrections from these data follows an iterative approach in which the calibration of one detector of a coincident pair is combined with knowledge of the source locations and scanner geometry to improve the calibration of the other. The procedure is successively iterated for each detector of the pair until a desired level of accuracy is achieved for both. The accuracy and speed of the method is found to be comparable to standard methods using both qualitative and quantitative measures